Semiconductor device and method for producing the same

ABSTRACT

There is provided a semiconductor device in which substantially no deformation of a bonded wire occurs, and a method for producing the semiconductor device. A wiring pattern of a wiring substrate and an electrode of an IC chip are connected by a wire. A contact prevention resin whose height is higher than the highest position of the bonded wire, is adhered to the approximate center of the surface of the IC chip. If the wiring substrate warps due to heat from the lower metallic mold, an inner surface of an upper metallic mold placed on the wiring substrate abuts against the contact prevention resin, and decrease warpage of the wiring substrate. Accordingly, the wire is kept from contacting the inner surface of the upper metallic mold. Thereafter, the IC chips, the wires, and the like are sealed by injecting a mold resin into the molds.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a resin seal type semiconductor device,and a method for producing the same.

2. Description of the Related Art

Recently, in keeping with the tendency toward high density packaging ofelectrical appliances, there has been increased demand for thin andsmall-sized semiconductor devices, and the production quantity of resinseal type packages such as Ball Grid Array/Chip Size Package (BGA/CSP)has increased. In these circumstances, in order to improve BGA/CSPproduction or the like, a production method using package molding/sawcutting techniques has been widely used where a plurality of integratedcircuit (IC) chips are fixed to one wiring substrate and sealed alltogether by mold resin. Thereafter, the wiring substrate is cut intoseparate semiconductor devices.

FIG. 2 is a cross sectional view showing an example of a conventionalsemiconductor device.

The semiconductor device shown in this drawing is that of BGA/CSP typeproduced by using package molding/saw cutting technique. An IC chip 3 isfixed onto a wiring substrate 1 by an adhesive agent 2. The wiringsubstrate 1 is, for example, formed of a glass/epoxy substrate having athickness of 0.2 mm or thereabouts. Wiring patterns 1 a and 1 b arerespectively formed on face and reverse surfaces of the wiring substrate1 in the periphery thereof and are electrically connected to each othervia a through hole 1 c.

The wiring pattern 1 a formed on the face surface of the wiringsubstrate 1 and an electrode 3 a on the surface of the IC chip 3 areconnected by a wire 4 such as gold wire. The surface of the wiringsubstrate 1 is sealed by a mold resin 5 having a predetermined thicknessso as to protect the IC chip 3 and the wire 4. A soldering ball 6 havinga diameter of 0.5 mm or thereabouts is attached to the wiring pattern 1b formed on the reverse surface of the wiring substrate 1 so as to makeconnection with a printed circuit board or the like.

Such semiconductor devices as above are produced by the followingprocess.

First, a wiring substrate is produced in which plural sets of wiringpatterns 1 a and 1 b, and through holes 1 c are arranged, correspondingto each of the plural IC chips 3, in transverse and vertical directionsin a region around a corresponding IC chip 3. Subsequently, the pluralIC chips 3 are each fixed by the adhesive agent 2 to a predeterminedposition on the wiring substrate, and an electrode 3 a on the surface ofthe IC chip 3 and the wiring pattern 1 a corresponding thereto areconnected by the wire 4 for wire bonding.

Further, the wiring substrate on which the plural IC chips 3 are mountedis placed on a lower metallic mold heated to 170° C. or thereabouts, anda corresponding upper metallic mold is placed thereon. The mold resin 5is injected from an injection hole formed in the upper metallic moldinto an interior of the molds and a cavity formed by an inner surface ofthe upper metallic mold, and the wiring substrate is sealed by the moldresin 5.

After the mold resin 5 has been cured, the wiring substrate of whichsurface is sealed by the mold resin 5, is taken out by releasing theupper and lower metallic molds therefrom. The resin-sealed wiringsubstrate is cut into separate semiconductor devices corresponding tothe IC chips 3 by using a cutting saw. The soldering ball 6 is attachedto the wiring pattern 1 b on the reverse side of each of the separatewiring substrates 1, to thereby form a complete semiconductor device.Thus, productivity markedly improves as compared with a method in whichwiring semiconductor devices are separately molded one by one.

However, the above-described structure of semiconductor devices andmethod for producing the same, which have been conventionally known,have the following problems.

When the wiring substrate having dimensions of, for example 60 mm×180mm, is placed on a lower metallic mold heated to 170° C. or thereabouts,the wiring substrate is warped due to heat from the lower metallic moldand a portion of the wiring substrate may be raised from the lowermetallic mold. When the upper metallic mold is placed on the wiringsubstrate in the above-described state, there exists a problem in whichthe bonded wire 4 contacts the inner surface of the upper metallic moldand thereby deforms. In this regard, there is a risk of causingshort-circuits due to deformed wires 4 contacting each other.

SUMMARY OF THE INVENTION

The present invention has been devised to solve the above-describedproblems existing in the conventional method, and an object of thepresent invention is to provide a semiconductor having a structure inwhich reduced deformation of a bonded wire occurs, and a method forproducing the semiconductor device.

In order to solve the above-described problem, in accordance with afirst aspect of the present invention, there is provided a method forproducing a semiconductor device, comprising the steps of: (a) bonding aplurality of semiconductor elements onto a wiring substrate, the wiringsubstrate having a wiring pattern formed thereon for externalconnection, and each semiconductor having a surface with an electrodethereon; (b) connecting the electrode on the surface of each of thesemiconductor elements to the wiring pattern on the wiring substratewith a metal wire; (c) fixing a contact prevention resin having apredetermined height to the surface of at least one of the plurality ofsemiconductor elements; (d) placing the wiring substrate, with thesurface of each of the semiconductor elements facing upward, in a lowermetallic mold for mold processing; (e) putting an upper metallic moldfor mold processing on the wiring substrate placed in the lower metallicmold; (f) injecting mold resin into a space formed between the wiringsubstrate and the upper metallic mold for sealing the semiconductorelement and the metal wire on the wiring substrate; and (g) cutting thewiring substrate sealed by the mold resin into portions corresponding tothe plurality of semiconductor elements to thereby form a plurality ofsemiconductor devices.

In the first aspect of the present invention, since the above-describedmethod for producing a semiconductor device is provided, the followingoperation is performed.

A plurality of semiconductor elements are bonded onto a wiring substrateon which wiring patterns are formed corresponding to the plurality ofsemiconductor elements. Further, an electrode on the surface of each ofthe semiconductor elements and a wiring pattern corresponding theretoare connected by a metal wire and contact prevention resin having apredetermined height is fixed to the surface of each of thesemiconductor elements. The wiring substrate on which the plurality ofsemiconductor elements are mounted, is placed on the lower metallic moldfor mold processing, and an upper metallic mold is placed on the wiringsubstrate. The mold resin is injected into the space formed between theupper metallic mold and the wiring substrate, thereby sealing the wiringsubstrate. The wiring substrate sealed by the mold resin is cut intoportions corresponding to the semiconductor elements, thereby forming aplurality of semiconductor devices.

In accordance with a second aspect of the present invention, there isprovided a method for producing a semiconductor device, comprising thesteps of: (a) bonding a plurality of semiconductor elements onto awiring substrate, the wiring substrate having a wiring pattern forexternal connection formed thereon, and each semiconductor having asurface with an electrode thereon; (b) connecting the electrode on thesurface of each semiconductor element to the wiring pattern on thewiring substrate with a metal wire; (c) placing, in a lower metallicmold for mold processing, the wiring substrate with the surfaces of thesemiconductor elements facing upward; (d) placing an upper metallic moldfor mold processing on the wiring substrate placed in the lower metallicmold, the upper mold having a contact prevention protruding portion onan internal surface of the upper metallic mold; (e) injecting mold resininto a space formed between the wiring substrate and the upper metallicmold sealing the semiconductor element and the metal wire on the wiringsubstrate; and (f) cutting the wiring substrate sealed by the mold resininto portions corresponding to the plurality of semiconductor elementsto thereby form a plurality of semiconductor devices.

In the second aspect of the present invention, preferably, theprotruding portion on the internal surface of the upper metallic mold isformed at a position corresponding substantially to the center of atleast one of the plurality of semiconductor elements bonded to thewiring substrate, and a dimension of the protruding portion in adirection in which it protrudes is greater than a distance between thesurface of the semiconductor element and a highest maximum position ofthe metal wire, and smaller than a height of the mold resin injectedonto the semiconductor element, relative to surfaces of thesemiconductor element.

Further, in the second aspect of the present invention, preferably, theprotruding portion on the internal surface of the upper metallic mold isformed at a boundary between the semiconductor elements, and a dimensionof the protruding portion in a direction to which it protrudes is equalto a height of a space formed between the wiring substrate and the uppermetallic mold.

In the above-described first and second aspects of the presentinvention, the following operation is performed.

A plurality of semiconductor elements are bonded onto a wiring substrateon which wiring patterns are formed corresponding to the plurality ofsemiconductor elements. An electrode on the surface of each of thesemiconductor elements and a wiring pattern corresponding thereto areconnected by a metal wire. The wiring substrate on which the pluralityof semiconductor elements are mounted, is placed on a lower metallicmold for mold processing. An upper metallic mold having a contactprevention protruding portion formed inside thereof, is placed on thewiring substrate. Mold resin is injected into a space formed between theupper metallic mold and the wiring substrate, thereby sealing the wiringsubstrate. The wiring substrate sealed by the mold resin is cut intoportions corresponding to the semiconductor elements, thereby forming aplurality of semiconductor devices.

In accordance with a third aspect of the present invention, there isprovided a semiconductor device comprising: (a) a semiconductor elementhaving a plurality of electrodes on the surface thereof; (b) a wiringsubstrate having a wiring pattern for external connection, to whichwiring substrate the semiconductor element is fixed by an adhesive agentapplied to a reverse surface thereof; (c) a metal wire connecting theplurality of electrodes on the semiconductor element to the wiringpattern of the wiring substrate; (d) contact prevention resin having apredetermined height, fixed substantially at the center of the surfaceof the semiconductor element; and (e) mold resin sealing and protectingthe surface of the wiring substrate, the semiconductor element, themetal wire, and the contact prevention resin.

According to the first aspect of the present invention, the contactprevention resin having a predetermined height is adhered to the surfaceof each of the semiconductor elements. As a result, even if the wiringsubstrate warps due to heating or the like, when the upper metallic moldfor mold processing is placed on the wiring substrate, the inner surfaceof the upper metallic mold abuts against the contact prevention resin,and thus the metal wire is protected. Therefore, there is reduced riskof deforming the metal wire.

According to the second aspect of the present invention, the contactprevention protruding portion is formed at the inner side of the uppermetallic mold for mold processing. As a result, even if the wiringsubstrate warps, the metal wire is protected by the protruding portionof the upper metallic mold when the upper metallic mold is placed on thewiring substrate. Accordingly, there is reduced risk of deforming themetal wire.

Further, in the second aspect of the present invention, the protrudingportion provided inside of the upper metallic mold is preferably formedat a position corresponding substantially to the center of thesemiconductor element bonded onto the wiring substrate in such a mannerthat the dimension of the protruding portion in a direction to which itprotrudes is greater than a distance between the surface of thesemiconductor element and the highest position of the metal wireconnected to the semiconductor element, and is also smaller than theheight of the mold resin injected onto the semiconductor element fromthe semiconductor element surface. As a result, even if the wiringsubstrate warps, the protruding portion of the upper metallic mold abutsagainst the surface of the semiconductor element when the upper metallicmold is placed on the wiring substrate, and the metal wire is therebyprotected.

Moreover, in the second aspect of the present invention, the protrudingportion provided inside of the upper metallic mold is preferably formedat a position corresponding to a boundary between the plurality ofsemiconductor devices in such a manner that the height of the protrudingportion is substantially equal to that of the mold resin formed on thesemiconductor element. As a result, even if the wiring substrate warps,the protruding portion of the upper metallic mold abuts against thewiring substrate at a position corresponding to the boundary between thesemiconductor devices with the upper metallic mold placed on the wiringsubstrate. Accordingly, warp of the wiring substrate is suppressed andthe metal wire is thereby protected.

According to the third aspect of the present invention, the contactprevention resin having a predetermined height is fixed to the surfaceof each of the semiconductor elements. As a result, when mold processingis carried out in which the semiconductor elements are mounted alltogether on the wiring substrate, even if the wiring substrate warps,the inner surface of the upper metal mold placed on the wiring substrateabuts against the contact prevention resin and the metal wire is therebyprotected. Accordingly, there is reduced risk of deforming the metalwire.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are each a structural diagram of a semiconductor deviceaccording to a first preferred embodiment of the present invention.

FIG. 2 is a cross sectional view showing an example of a conventionalsemiconductor device.

FIGS. 3A, 3B, and 3C are explanatory diagrams showing a method forproducing the semiconductor device shown in FIGS. 1A and 1B.

FIGS. 4A, 4B, and 4C are explanatory diagrams showing a method forproducing a semiconductor device according to a second preferredembodiment of the present invention.

FIGS. 5A, 5B, and 5C are explanatory diagrams showing a method forproducing a semiconductor device according to a third preferredembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

FIGS. 1A and 1B are each a structural diagram of a semiconductor deviceaccording to a first preferred embodiment of the present invention. FIG.1A is a plan view and FIG. 1B is a cross sectional view taken along theline A—A in FIG. 1A. In FIGS. 1A and 1B, the same members as those inFIG. 2 are denoted by the same reference numerals.

The semiconductor device shown in FIGS. 1A and 1B is that of BGA/CSPtype produced by package molding/saw cutting techniques. A semiconductorelement 3 (for example, an IC chip) is fixed onto a wiring substrate 1by an adhesive agent 2. The wiring substrate 1 is formed of, for examplea glass/epoxy substrate having a thickness of 0.2 mm or thereabouts andtransverse and vertical dimensions of approximately 5 to 15 mm. Wiringpatterns 1 a and 1 b are respectively formed on face and reversesurfaces of the wiring substrate 1 in the periphery thereof. Further,the wiring patterns 1 a and 1 b are electrically connected to each othervia a through hole 1 c.

The wiring pattern 1 a on the face surface of the wiring substrate 1 andan electrode 3 a on the surface of the IC chip 3 are connected to eachother by metal wire 4 (for example, gold wire) which is bonded to thewiring pattern 1 a and to the electrode 3 a. Further, a contactprevention resin 7 adheres to a central portion on the surface of the ICchip 3. The height of the contact prevention resin 7 is set so as to behigher than the highest position of the bonded wire 4.

The surface of the wiring substrate 1 is sealed by a mold resin 5 havinga predetermined thickness so as to protect the IC chip 3, the wire 4,and the like. Furthermore, a soldering ball 6 having a diameter ofapproximately 0.5 mm is attached to the wiring pattern 1 b on thereverse surface of the wiring substrate 1 for connection to a printedcircuit board or the like.

FIGS. 3A to 3C are explanatory diagrams showing a method for producingthe semiconductor device shown in FIGS. 1A and 1B. With reference toFIGS. 3A to 3C, the method for producing the semiconductor device shownin FIGS. 1A and 1B will be described hereinafter.

As illustrated in FIG. 3A, first, a wiring substrate 1X is produced inwhich plural sets of wiring patterns 1 a and 1 b, and through holes 1 care arranged, corresponding to each of the plural (in this case, four)IC chips 3, in transverse and vertical directions in a region around acorresponding IC chip 3. The wiring substrate 1X has dimensions ofapproximately 60 mm (width)×180 mm (length)×0.2 mm (thickness). Theplural IC chips 3 are each fixed by an adhesive agent 2 (see FIG. 1B) ata predetermined position on the wiring substrate 1X. The electrode 3 aon the surface of each IC chip 3 and the wiring pattern 1 acorresponding thereto are connected to each other by wire 4, which isbonded to the electrode 3 a and the wiring pattern 1 a. Further, thecontact prevention resin 7 is adhered to a central portion on thesurface of each IC chip 3.

Next, as illustrated in FIG. 3B, the wiring substrate 1X on which the ICchips 3 are mounted is placed on a lower metallic mold 11 heated toapproximately 170° C., and a corresponding upper metallic mold 12 isplaced thereon. At this time, if an amount of warp caused in the wiringsubstrate 1X is greater than a clearance between the contact preventionresin 7 and the upper metallic mold 12, the contact prevention resin 7,rather than the wire 4, first contacts the upper metallic mold 12. As aresult, the inner surface of the upper metallic mold 12 and the wire 4are kept from contacting each other, and the final amount of warp causedin the wiring substrate 1X decreases.

After the wiring substrate 1X has been interposed between the upper andlower metallic molds 12 and 11, the mold resin 5 is injected into themolds from an injection hole 13 provided in the upper metallic mold 12at a predetermined pressure. As a result, the mold resin 5 is injectedinto a cavity formed between the inner surface of the upper metallicmold 12 and the wiring substrate 1X and the wiring substrate 1X ispushed against the lower metallic mold 11 due to pressure applied to themold resin 5. Therefore, the warp of the wiring substrate 1X iscorrected.

Further, as illustrated in FIG. 3C, after the mold resin 5 has beencured, the upper and lower metallic molds 12 and 11 are removed and thewiring substrate 1X of which its surface is sealed by the mold resin 5,is removed. The wiring substrate 1X thus molded is cut intosemiconductor devices corresponding to the IC chips 3 by using a cuttingsaw. A soldering ball 6 is attached to the wiring pattern 1 b on thereverse surface of each of separate wiring substrates 1, and thesemiconductor device shown in FIGS. 1A and 1B is thus completed.

As described above, the semiconductor device according to the firstembodiment is produced in such a manner that after the contactprevention resin 7 whose height is higher than the highest position ofthe bonded wire 4, is adhered to the surface of each of the IC chips 3mounted on the wiring substrate 1X. The wiring substrate 1X is sealed bythe mold resin 5 while interposed between the upper and lower metallicmolds 12 and 11. As a result, there is insignificant risk that when thewiring substrate 1X is interposed between the upper and lower metallicmodes 12 and 11, that the wire 4 contacts the inner surface of the uppermetallic mold 12, thereby preventing deformation of the wire 4 and shortcircuits caused by deformed wires 4 contacting each other.

Second Embodiment

FIGS. 4A to 4C are explanatory diagrams showing a method for producing asemiconductor device according to a second preferred embodiment of thepresent invention. It should be noted that the same members as those inFIGS. 3A to 3C will be denoted by the same reference numerals.

In the above-described production method shown in FIGS. 3A to 3C, thecontact prevention resin 7 adheres to the surface of the IC chip 3 so asto prevent the wire 4 from contacting the inner surface of the uppermetallic mold 12. In comparison, in the production method shown in FIGS.4A to 4C, an upper metallic mold 12A is used which has contactprevention protruding portions 12 a formed at the inner side of theupper metallic mold at positions corresponding to respective centralportions on the surfaces of the IC chips 3.

Referring now to FIGS. 4A to 4C, the method for producing asemiconductor device according to the second embodiment will bedescribed hereinafter.

As illustrated in FIG. 4A, first, the wiring substrate 1X is produced inwhich plural sets of wiring patterns 1 a and 1 b, and through holes 1 care arranged, corresponding to each of the plural IC chips 3, intransverse and vertical directions in a region around a corresponding ICchip 3. The IC chips 3 are fixed by adhesive agents 2 at theirrespective predetermined positions on the wiring substrate 1X. Theelectrode 3 a on the surface of each IC chip 3 and the wiring pattern 1a corresponding thereto are connected to each other by wire 4 bonded tothe electrode 3 a and to the wiring pattern 1 a.

Subsequently, as illustrated in FIG. 4B, the wiring substrate 1X onwhich the IC chips 3 are mounted, is placed on the lower metallic mold11 heated to 170° C. or thereabouts, and the corresponding uppermetallic mold 12A is placed thereon. As described above, the uppermetallic mold 12A has the contact prevention protruding portions 12 aformed at the inner side thereof at positions corresponding torespective central portions on the surfaces of the IC chips 3. Theheightwise dimension of the protruding portion 12 a is set so as to begreater than a distance from the surface of the IC chip 3 to the highestposition of the bonded wire 4 and also smaller than the heightwisedimension of the mold resin 5 formed on the IC chip 3.

When an amount of warp caused in the wiring substrate 1X is greater thanthe heightwise dimension of the protruding portion 12 a formed in theupper metallic mold 12A, the upper metallic mold 12A will thereforefirst contacts the surface of the IC chip 3, rather than the wire, viathe protruding portion 12 a. As a result, the inner surface of the uppermetallic mold 12A and the wire 4 are kept from contacting each other andthe final amount of warp of the wiring substrate 1X decreases.

After the wiring substrate 1X has been interposed between the upper andlower metallic molds 12A and 11, mold resin 5 is injected into the moldsfrom the injection hole 13 formed in the upper metallic mold 12A at apredetermined pressure. Thus, the mold resin 5 is injected into a cavityformed between the inner surface of the upper metallic mold 12A and thewiring substrate 1X, and the wiring substrate 1X is pushed against thelower metallic mold 11 due to a pressure applied to the mold resin 5. Asa result, the warp of the wiring substrate 1X is corrected.

Further, as illustrated in FIG. 4C, after the mold resin 5 has beencured, the upper and lower metallic molds 12A and 11 are removed and thewiring substrate 1X of which its surface is sealed by the mold resin 5is removed. The mold resin 5 after having been removed from the moldshas concave portions 5 a formed by the protruding portions 12 a of theupper metallic mold 12A at positions corresponding to the respectivecentral portions of the IC chips 3. The subsequent process is carriedout in the same manner as in the first embodiment.

As described above, in the method for producing a semiconductor deviceaccording to the second embodiment, the upper metallic mold 12A has theprotruding portions 12 a whose heightwise dimension is greater than thedistance between the surface of the IC chip 3 mounted on the wiringsubstrate 1X to the highest position of the wire 4 formed by bonding onthe surface of the IC chip 3 and is smaller than the heightwisedimension of the mold resin 5 formed on the IC chip 3. The mold resin 5is injected into the molds with the wiring substrate 1X interposedbetween the upper and lower metallic molds 12A and 11. As a result,there is insignificant risk that when the wiring substrate 1X isinterposed between the upper and lower metallic molds 12A and 11, thatthe wire 4 contacts the upper metallic mold 12A, and deformation of thewire 4 is thereby prevented. Accordingly, occurrence of short circuitscaused by deformed wires 4 contacting each other is prevented.

Further, it is not necessary that the contact prevention resin 7 adheresto the surface of the IC chip 3. Therefore, the production process issimplified as compared with the first embodiment.

Third Embodiment

FIGS. 5A to 5C are explanatory diagrams showing a method for producing asemiconductor device according to a third preferred embodiment of thepresent invention. Note that the same members as those in FIGS. 4A to 4Cwill be denoted by the same reference numerals.

The production method shown in FIGS. 5A to 5C is different from theproduction method shown in FIGS. 4A to 4C in the position and dimensionsof the contact prevention protruding portion formed at the inner side ofthe upper metallic mold.

That is, the upper metallic mold 12A shown in FIG. 4B has the contactprevention protruding portions 12 a on the inner surface of the uppermetallic mold 12A at the positions corresponding to the respectivecentral portions on the surfaces of the IC chips 3 so as to prevent thewire 4 from contacting the inner surface of the upper metallic mold 12A.On the other hand, an upper metallic mold 12B shown in FIG. 5B has awarp prevention protruding portion 12 b formed at a positioncorresponding to a boundary at which, when the wiring substrate forwhich molding is completed, will be separated into differentsemiconductor devices. The protruding portion 12 b has the sameheightwise dimension as that of the internal space formed by the uppermetallic mold 12B and the wiring substrate 1X. That is, when the uppermetallic mold 12B is put on the wiring substrate 1X, the protrudingportion 12 b contacts the surface of the wiring substrate 1X and warp ofthe wiring substrate 1X is thereby suppressed or corrected.

Referring now to FIGS. 5A to 5C, the method for producing asemiconductor device according to the third embodiment will be describedhereinafter.

As illustrated in FIG. 5A, first, the wiring substrate 1X is produced inwhich plural sets of wiring patterns 1 a and 1 b, and through holes 1 care arranged, corresponding to each of the plural IC chips 3, intransverse and vertical directions in a region around a corresponding ICchip 3. The IC chips 3 are each fixed by the adhesive agent 2 at apredetermined position on the wiring substrate 1X, and the electrode 3 aon the surface of each IC chip 3 and the wiring pattern 1a correspondingthereto are connected to each other via the wire 4. The wire 4 is bondedto the electrode 3 a and to the wiring pattern 1 a.

Next, as shown in FIG. 5B, the wiring substrate 1X on which the IC chips3 are mounted is placed on the lower metallic mold 11 heated to 170° C.or thereabouts, and the corresponding upper metallic mold 12B is placedthereon. The upper metallic mold 12B has, as described above, theprotruding portion 12 b for preventing warp of the wiring substrate 1X,formed at the inner side of the mold at a position corresponding to theboundary, which will later be cut to form separate semiconductordevices. As a result, the warp of the wiring substrate 1X is suppressedor corrected and the inner surface of the upper metallic mold 12B andthe wire 4 are kept from contacting each other.

After the wiring substrate 1X has been interposed between the upper andlower metallic molds 12B and 11, the mold resin 5 is injected into themolds from the injection hole 13 formed in the upper metallic mold 12Bat a predetermined pressure.

Further, as illustrated in FIG. 5C, after the mold resin 5 has beencured, the upper and lower metallic molds 12B and 11 are removed and thewiring substrate 1X of which its surface is sealed by the mold resin 5,is removed. The mold resin 5 thus obtained has a region with no resinformed, at the boundary between semiconductor devices corresponding tothe protruding portion 12 b of the upper metallic mold 12B. Thesubsequent process is the same as that of the first embodiment.

As described above, in the method for producing a semiconductor deviceaccording to the third embodiment, the upper metallic mold 12B havingthe protruding portion 12 b for correcting the warp of the wiringsubstrate 1X at the position corresponding to the boundary betweensemiconductor devices on the wiring substrate 1X is placed on the wiringsubstrate 1X, and the mold resin 5 is injected into the molds. As aresult, there is no significant risk that when the wiring substrate 1Xis interposed between the upper and lower metallic molds 11 and 12B,that the wire 4 contacts the upper metallic mold 12B, thereby preventingdeformation of the wire 4 and occurrence of short circuits. Further, itis not necessary to adhere the contact prevention resin 7 to the surfaceof each of the IC chips 3. Therefore, the production process issimplified as compared with that of the first embodiment. Moreover,since the protruding portion 12 b is provided at the positioncorresponding to the boundary between semiconductor devices,substantially no pressure is applied to the IC chips 3 or the like whenthe wiring substrate 1X is interposed between the upper and lowermetallic molds 11 and 12B. Therefore, the improvement in the quality ofthe resulting product can be expected.

The present invention is not limited to the above-described embodimentsand various modifications can be made. Examples of modification includethe following cases (a) to (e):

(a) The shape and dimensions of the wiring substrate 1X and the numberof semiconductor devices produced all together on the wiring substrate1X are not limited to the examples illustrated in the above-describedembodiments;

(b) The semiconductor device shown in FIGS. 1A and 1B has the solderingball 6 connected externally, but there are cases in which no solderingball may be required depending on the method of connection to a printedcircuit board;

(c) In the method for producing a semiconductor device shown in FIGS. 3Ato 3C, the contact prevention resin 7 is attached to each of thesurfaces of all IC chips 3, but the contact prevention resin 7 does notnecessarily need to be attached to each of the surfaces of all IC chips3. It suffices that the contact prevention resin 7 be attached to eachof the surfaces of the required IC chips 3 at a proper interval inaccordance with warpage of the wiring substrate 1X;

(d) In the production method shown in FIGS. 4A to 4C, the upper metallicmold 12A includes the protruding portions 12 a formed at the inner sideof the mold at the positions corresponding to all IC chips 3, but theprotruding portions 12 a does not necessarily need to be provided forall of the IC chips 3. It suffices that the protruding portions 12 a maybe provided at a proper interval in accordance with warpage of thewiring substrate 1X; and

(e) In the upper metallic mold 12B used in the production method shownin FIGS. 5A to 5C, the position of the protruding portion 12 b is notlimited to the position indicated in FIG. 5B. The protruding portion 12b may be provided at an arbitrary position so long as the warp of thewiring substrate 1X can be corrected without adversely affecting the ICchips 3 and the wire 4.

What is claimed is:
 1. A method for producing a semiconductor device,comprising the steps of: (a) bonding a plurality of semiconductorelements onto a wiring substrate, the wiring substrate having a wiringpattern formed thereon for external connection, and each of thesemiconductor elements having a surface with an electrode thereon; (b)connecting the electrode on the surface of each of the semiconductorelements to the wiring pattern on the wiring substrate with a metalwire; (c) fixing a contact prevention resin to the surface of at leastone of the plurality of semiconductor elements, the contact preventionresin being at a position corresponding substantially to the center ofthe at least one semiconductor element, and being sized so as not tocover the electrode on, and the metal wire connected to, the at leastone semiconductor element; (d) placing the wiring substrate, with thesurface of each of the semiconductor elements facing upward, in a lowermetallic mold for mold processing; (e) putting an upper metallic mold onthe wiring substrate placed in the lower metallic mold, the uppermetallic mold including a protruding portion which contacts the wiresubstrate at the periphery thereof for molding processing, to preventwarping of the wiring substrate; (f) injecting mold resin into a spacebetween the wiring substrate and the upper metallic mold for sealing thesemiconductor elements and the metal wires on the wiring substrate; and(g) cutting the wiring substrate sealed by the mold resin into portionscorresponding to the plurality of semiconductor elements to thereby forma plurality of semiconductor devices.
 2. A method for producing asemiconductor device according to claim 1, wherein the contactprevention resin has a predetermined height that is selected to behigher than a maximum height of metal wire above the surface of any ofthe semiconductor elements.
 3. A method for producing a semiconductordevice according to claim 1, wherein the contact prevention resin isfixed to the surfaces of each of the semiconductor elements.
 4. A methodfor producing a semiconductor device, comprising the steps of: (a)bonding a plurality of semiconductor elements onto a wiring substrate,the wiring substrate having a wiring pattern for external connectionformed thereon, and each of the semiconductor elements having a surfacewith an electrode thereon; (b) connecting the electrode on the surfaceof each of the semiconductor elements to the wiring pattern on thewiring substrate with a metal wire; (c) placing, in a lower metallicmold for mold processing, the wiring substrate with the surfaces of thesemiconductor elements facing upward; (d) placing an upper metallic moldfor mold processing on the wiring substrate placed in the lower metallicmold, the upper mold having a contact prevention protruding portion onan internal surface of the upper metallic mold; (e) injecting mold resininto a space between the wiring substrate and the upper metallic moldsealing the semiconductor elements and the metal wires on the wiringsubstrate; and (f) cutting the wiring substrate sealed by the mold resininto portions corresponding to the plurality of semiconductor elementsto thereby form a plurality of semiconductor devices; wherein theprotruding portion on the internal surface of the upper metallic mold isformed at a position corresponding substantially to the center of atleast one of the plurality of semiconductor elements bonded to thewiring substrate, and a dimension of the protruding portion in adirection in which it protrudes is greater than a distance between thesurface of the semiconductor element and a highest maximum position ofthe metal wire, and smaller than a height of the mold resin injectedonto the semiconductor element, relative to the surfaces of thesemiconductor element.
 5. A method for producing a semiconductor device,comprising the steps of: (a) bonding a plurality of semiconductorelements onto a wiring substrate, the wiring substrate having a wiringpattern for external connection formed thereon, and each of thesemiconductor elements having a surface with an electrode thereon; (b)connecting the electrode on the surface of each of the semiconductorelements to the wiring pattern on the wiring substrate with a metalwire; (c) placing, in a lower metallic mold for mold processing, thewiring substrate with the surfaces of the semiconductor elements facingupward; (d) placing an upper metallic mold for mold processing on thewiring substrate placed in the lower metallic mold, the upper moldhaving a contact prevention protuding portion on an internal surface ofthe upper metallic mold; (e) injecting mold resin into a space betweenthe wiring substrate and the upper metallic mold sealing thesemiconductor elements and the metal wires on the wiring substrate; and(f) cutting the wiring substrate sealed by the mold resin into portionscorresponding to the plurality of semiconductor elements to thereby forma plurality of semiconductor devices; wherein the protruding portion onthe internal surface of the upper metallic mold is formed at a positioncorresponding substantially to the center of at least one of theplurality of semiconductor elements bonded to the wiring substrate, anda dimension of the protruding portion in a direction in which itprotrudes is greater than a distance between the surface of thesemiconductor element and a highest maximum position of the metal wire,and smaller than a height of the mold resin injected onto thesemiconductor element, relative to the surfaces of the semiconductorelement.
 6. A method for producing a semiconductor device, comprisingthe steps of: (a) bonding a plurality of semiconductor elements onto awiring substrate, the wiring substrate having a wiring pattern forexternal connection formed thereon, and each of the semiconductorelements having a surface with an electrode thereon; (b) connecting theelectrode on the surface of each of the semiconductor elements to thewiring pattern on the wiring substrate with a metal wire; (c) placing,in a lower metallic mold for mold processing, the wiring substrate withthe surfaces of the semiconductor elements facing upward; (d) placing anupper metallic mold for mold processing on the wiring substrate placedin the lower metallic mold, the upper mold having a contact preventionprotruding portion on an internal surface of the upper metallic mold;(e) injecting mold resin into a space between the wiring substrate andthe upper metallic mold sealing the semiconductor elements and the metalwires on the wiring substrate; and (f) cutting the wiring substratesealed by the mold resin into portions corresponding to the plurality ofsemiconductor elements to thereby form a plurality of semiconductordevices; wherein the protruding portion on the internal surface of theupper metallic mold is formed at a boundary between the semiconductorelements, and a dimension of the protruding portion in a direction inwhich it protrudes is equal to a height of a space formed between thewiring substrate and the upper metallic mold.